Defensive publication

ABSTRACT

THERMOPLASTIC RANDOM GRAFT COPOLYMERS, HAVING A BACKBONE CHAIN MADE OF AN ELASTOMER AND UP TO 60 WEIGHT PERCENT OF CRYSTALLIZABLE SIDE-CHAINS WITH AN AVERAGE LENGTH OF 3 TO 1000 ALPHA-SUBSTITUTED-BETA-PROPIOLACTTONE MONOMER UNITS ATTACHED TO ABOUT 0.02 TO 1.0 MOLE OF RANDOM ANIONIC GRAFTING SITES PER KILOGRAM OF SAID BACKBONE ELASTOMER, ARE HEAT TREATED IN THE ABSENCE OF NUCLEATING AGENTS AND STRESS TO A TEMPERATURE ABOVE 70*C. BUT BELOW THEIR MELT FLOW TEMPERATURE TO IMPROVE THEIR COMPRESSION SET RESISTANCE. PREFERRED GRAFT COPOLYMERS HAVE BACKBONE CHAINS MADE FROM POLY(ETHYL ACRYLATE) OR ETHYLENE/PROPYLENE/NON-CONJUGATED DIENE COPOLYMERS (EPDM) MODIFIED WITH MALEIC ANHYDRIDE OR THIOGLYCOLIC ACID; THEIR SIDE-CHAINS ARE MADE FROM PIVALOLACTONE. CARBON BLACK, OIL, PIGMENTS, ANTIOXIDANTS, ETC., CAN BE PRESENT. EPDM-MALEIC ANHYDRIDE GRAFT COPOLYMERS ARE PREFERABLY TREATED AT TEMPERATURES ABOVE THE ENVIRONMENTAL TEMPERATURE TO WHICH THEY WILL BE SUBJECTED, TREATMENT TIME WILL VARY WITH THE PARTICULAR GRAFT COPOLYMER AND IS PREFERABLY ONE TO EIGHT HOURS. THE TREATED GRAFT COPOLYMERS SHOULD NOT SUBSEQUENTLY BE HEATED ABOVE THEIR MELTING POINT OR WHILE THEY ARE UNDER TENSION OR COMPRESSION (CAUSING PERMANENT CHANGE OF DIMENSION).

DEFENSIVE PUBLICATION UNITED STATES PATENT OFFICE Published at therequest of the applicant or owner in accordance with the Notice of Dec.516, 1969, 869 O.G. 687. The abstracts of Defensive Publicationapplications are identified by distinctly numbered series and arearranged chronologically. The heading of each abstract indicates thenumber of pages of specification, including claims and sheets ofdrawings contained in the application as originally filed. The files ofthese applications are available to the public for inspection andreproduction may be purchased for 30 cents a sheet.

Defensive Publication applications have not been examined as to themerits of alleged invention. The Patent Ofiice makes no assertion as tothe novelty of the disclosed subject matter.

PUBLISHED APRIL 9, 1974 T921,008 HEAT TREATMENT OF CERTAIN ELASTOMER/ALPHA-SUBSTITUTED BETA-PROPIOLACIONE GRAFT COPOLYMERS TO IMPROVEPHYSICAL PROPERTIES THEREOF Richard Charles Thamm, Wilmington, DeL,assignor to E. I. du Pont de Nemours and Company, Wilmington,

Filed Jan. 16, 1973, Ser. No. 324,164 Int. Cl. B29c 25/00 U.S. Cl.264-85 No Drawing. 31 Pages Specification Thermoplastic random graftcopolymers, having a backbone chain made of an elastomer and up to 60weight percent of crystallizable side-chains with an average length of 3to 1000 alpha-substituted-beta-propiolactone monomer units attached toabout 0.02 to 1.0 mole of random anionic grafting sites per kilogram ofsaid backbone elastomer, are heat treated in the absence of nucleatingagents and stress to a temperature above 70 C. but below their melt flowtemperature to improve their compression set resistance. Preferred graftcopolymers have backbone chains made from poly(ethyl acrylate) orethylene/propylene/non-conjugated diene copolymers (EPDM) modified withmaleic anhydride or thiogiycolic acid; their side-chains are made frompivalolactone. Carbon black, oil, pigments, antioxidants, etc., can bepresent. EPDM-maleic anhydride graft copolymers are preferably treatedat temperatures above the environmental temperature to which they willbe subjected. Treatment time will vary with the particular graftcopolymer and is preferably one to eight hours. The treated graftcopolymers should not subsequently be heated above their melting pointor while they are under tension or compression (causing permanent changeof dimension).

